The current knowledge regarding the course and the pathogenesis of a sepsis comes in large part from studies on the interaction between gram-negative bacteria and the human organism (Chest 1992; 101; 1644-1655). The primary agents for introducing a sepsis cascade accordingly produce bacterial endotoxins, a group of lipopolysaccharides from the cell wall of gram-negative bacteria. (Reviews Infect. Dis. 1983; 5; 733-747). Endotoxins, possibly the most potent fever-producing substances of all (pyrogens), activate above all monocytes and endothelial cells. The immune system is activated through the release of mediators or, as the case may be, the development of adhesive molecules, preparing a leukocytic suppression. This leads to a migration of the leukocytes into tissues with high chemotoxin content (site of local inflammation). If the local cause can be eliminated, then the inflammation process is impeded. If over a longer time period, either intermittently or continuously, this leads to an excessive influx of bacteria, endotoxins or other antigen-like acting cell products into the blood, then the useful defense reaction by monocytes and endothelial cells changes into an autoaggressive process with severe circulation dysfunction, secondary organ failures, coagulation disruptions (DIC), etc.; a sepsis (with positive proof of causative agent) or, as the case may be, a systemic inflammatory response syndrome (SIRS, no provable cause) develop and cause death in up to 30% of the cases where a simple sepsis is involved and up to 90% in patients where septic shock is involved. (Sepsis. An interdisciplinary challenge. Berlin, Heidelberg, New York: Springer Verlag, 1989).
Gram-positive causes of the genesis of sepsis have in recent years increasingly become an object of research study. Countless studies deal with the increased incidence of gram-positive sepsis in the last decade. Statistics show that now already 30 to 40% of all cases of sepsis can be traced back to gram-positive causes (Am J. Med. 1991; 91 (suppl. 3B): 72-89).
The treatment of bacterial sepsis in intensive-care medical centers is made additionally difficult because of increasing resistance to antibiotics.
Currently, sepsis is viewed as a multi-phasic illness in which a so-called hyperinflammatory phase with an excessive outpouring of pro-inflammatory cytokines, such as for example tumor-necrosis factor alpha (TNF alpha) or various interieukins (i.e. interleukin-1 and interieukin-6), joins with the germ-outpouring phase. Due to negative feedback, the course as it continues leads to an overflow change in anti-inflammatory cytokines (transformative growth factor beta=TGF beta, interleukin-4, interleukin-10, interleukin-13) and thus to the so-called immunoparalysis phase, which eventually leads to the patient""s death (Internist 1997; 38; 541-552). A clear definition of the individual phases based on concrete para-clinical values has, however, not yet been established.
Until today, the causal treatment of bacterial sepsis is possible only in stages. Next to antibiotic therapy, hopes rest on the application of anti-inflammatory substances that are currently being tested for their effects on gram-negative sepsis. (Nature. 1990; 348: 550-552, FASEB J. 1991; 5: 338-343). Some studies on this have already been completed and have until now yielded more often than not disappointing results. Thus, neither antibodies directed against the endotoxin lipid A (N. Engl. J. Med. 1991; 324; 429-436, JAMA 1991; 266; 1097-1102) nor anti-cytokine therapies against the tumor necrosis factor alpha (Crit. Care Med. 1993: 21; 318-327, JAMA 1995; 273; 934-941) nor interieukin-1 (JAMA 1994; 271; 1836-1842) could contribute to a reduction in the overall mortality rate. It seemed, however, that patients with very high cytokine levels at least partially benefited (Crit. Care Med. 1993; 21; 318-327, Crit. Care Med. 1996; 24; 733-742). The studies are, however, characterized by the large heterogeneity of the patient groups as well as the insufficient assignment until now of clinical studies on the course of sepsis.
A new approach is the use of pro-inflammatory cytokines (interferon gamma) in the immunoparalysis phase, which seemed promising in the first non-random studies, but which, however, still showed an over 30% mortality rate (Nature Medicine 1997; 3; 678-681). Legally registered patents for immunomodulatory substances, such as for example, some of the above described cytokine antagonists (WO 9406431 A1, U.S. Pat. Nos. 5,585,486, 5,585,357, 5,565,430, 5,552,400), mistel-lektine (DE 4221836 A1), fosfomycin (JP 09183730 A), macrocyclical substances (U.S. Nos. 5,527,907, 5,541,189, 5,541,193, 5,561,139, 5,561,140) or bacterial extracts (WO 8909607 A, EP 363491 A1). None of these approaches could show decisive therapeutic gains in sepsis therapy.
The therapeutic approaches known up until now were primarily implemented through in vivo administration of antibodies directed against cytokines or other cytokine-binding protein preparations and have produced no or only little therapeutic value. (Internist 1997; 38; 541-552, cf. 2, State of the Methodology).
Conditions of hyperinflammation or immunoparalysis lead to an increase in the blood plasma concentrations of a number of immunodeficient substances such as, for example, cytokines, which in part significantly disturb the processes of infection defense. The obliteration or addition of a single cytokine has until now not been a convincing therapeutic success. Rather, in demand is the useful removal of too-high concentrations of individual cytokines as well as the substitution of other cytokines that are present in too-diminished concentrations to stabilize the disrupted immune system.
The complexity of the problem of variable cytokine concentrations requires on the one hand sensitive measurement, on the other hand, however, it also requires the ability to quickly substitute the cytokines. However, because of the time delay in determining the cytokine concentration, substitution therapies in the form of injections/infusions can in the future only make a limited contribution to the solution. Constituting a new therapy is the use of cells, which, with their specific surface receptors, adsorb selectively and thus withdraw from circulation, but which, on the other hand, can also even form and release the underrepresented cytokines or other immunomodulatory effective molecules in the blood.